This invention relates to a temperature sensor for detecting the ambient temperature and, more particularly, to a temperature sensor which is designed to accurately detect temperature change by utilizing the thermal expansion and compression characteristics of a silicone rubber which are linear with respect to changes in temperature.
A proposed type of temperature sensor is constituted by a base plate, a thermally-expandable expanding agent coating applied to the base plate, a movable contact attached to the expanding agent coating, and a fixed contact disposed within the range of movement of the movable contact. In this temperature sensor, the movable contact is brought into electrical contact with the fixed contact by the thermal expansion of the expanding agent coating, thereby detecting a change in temperature (Japanese Utility Model Application No. 202539/1985).
This conventional temperature sensor is advantageous in that its shape and the distance between the contacts can be freely changed, and it is small and inexpensive. This sensor, however, cannot accurately detect temperature changes because the expansion characteristics of the expanding agent coating are not linear with respect to rise in temperature. Also, it is not possible to reuse this temperature sensor since, once the expanding agent coating has expanded, it cannot contract again. Moreover, there is a possibility that the expanding agent coating will be activated at an ordinary temperature below the set temperature and, therefore, this type of sensor lacks stability and needs to be handled carefully.